InSb PHOTODIODES (REVIEW. PART VI)

Abstract

In this review, a brief overview of epitaxial methods of growing single-crystal InSb films and their application for the manufacture of infrared photodiodes is provided. The results of growing InSb epitaxial films on Si and GaAs substrates are described. The main attention in the review is paid to InSb/CdTe heterostructures, which is explained by the almost perfect matching of their lattices and coefficients of thermal expansion. The properties of heterovalent InSb/CdTe interfaces as promising objects for spintronics and topological insulators are described. The results of experimental studies of InSb photodiodes for the mid-wavelength region of 3-5 μm, passivated with polycrystalline CdTe films by the hot wall epitaxy method are given. To investigate the electrical properties of polycrystalline fims, the direct conductivity was measured as a function of bias voltage and temperature. For this purpose, polycrystalline fims with a thickness of 200 to 1800 nm were grown on p-InSb substrates. The type of conductivity and resistivity of polycrystalline films were determined. Conclusions were made regarding the possibility of using this technique for effective and stable passivation. Photodiodes were characterized by measuring the dark current and the lifetime of minor carriers. Properties of heterovalent CdTe/InSb and isovalent CdTe/HgCdTe interfaces are compared. It is shown that they have different effects on the transport and photoelectric characteristics of photodiodes. It was established that when the passivation layer is deposited on the chemically etched surface of the mesa, an excess current of tunneling nature occurs in the photodiodes. The best results were obtained when surface treatment of the mesa includes the use of CP4A and HCl etchants, sulfidization in a non-aqueous Na 2 S solution, and deposition of a CdTe protective layer. Passivation of HgCdTe photodiodes using polycrystalline CdTe films does not affect the lifetime of charge carriers, but it needs improvement to achieve better stability of their characteristics.